If the text contains two fields, as it indeed seems so from your initial post, this approach might not help. Excuse me for missing that part.
As for using a string filter expression instead of int, I assume it might not work, since it will not match the syntax expected by the datasource that you use. You can see for yourself how the expressions will differ if you use string instead of int type of expression here:
(the table at the bottom)
Generally, you can build expressions that match the fields in the datasource. If you create an additional string field containing the two pieces of data, you will be able to filter by it. If you have two separate fields, you will need to build an expression for each of them separately and add them to the same group.
All the best,
the Telerik team
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